A liquid crystal display device is characterized by its thinness, low power consumption, high definition and the like, and, as a production technique of the liquid crystal display device has been developed, it becomes possible to manufacture a large-screen liquid crystal display device. Consequently, the liquid crystal display device becomes popular in a television field which has been occupied mainly by a cathode ray tube (CRT).
However, due to a display method of the liquid crystal display device, an image displayed in the liquid crystal display device has such a problem that the observer less clearly feels its contrast (low dynamic range) than that of CRT. In view of this problem, techniques for improving image quality have been actively developed in recent years.
For example, Patent Literature 1 discloses a liquid crystal display device including: a lighting section including a plurality of lighting regions for lighting the inside of an image display section; a light luminance control section for controlling a luminance of each lighting region of the lighting section in accordance with an input image signal; and an image signal conversion section for converting the input image signal in accordance with luminance information of each lighting region.
This liquid crystal display device increases a luminance of light for a display region (lighting region) containing a large amount of bright image information and adversely decreases a luminance of a light for a display region (lighting region) containing a large amount of dark image information, in accordance with an input image signal. Thereby, contrast of an entire screen of the liquid crystal display device can be more clearly felt (thereby its dynamic range is enhanced).
Further, in the liquid crystal display device, since a luminance of light is changed for each lighting region, a luminance of a display image varies between the lighting regions if the input image signal is inputted to a liquid crystal panel with its grayscale unadjusted. For this reason, in the technique of Patent Literature 1, the input image signal is converted in accordance with a light luminance for each lighting region and then is inputted to the liquid crystal panel. This reduces the variation of the same luminance of the display image between the respective lighting regions.
Further, in the liquid crystal display device, cross talk between the lighting regions causes not only light from a lighting region beneath a certain pixel of the liquid crystal panel but also light from an adjacent lighting region to be superimposed on light for the foregoing pixel (cross talk of light is generated). That is, incoming of the light from the adjacent lighting region causes an actual luminance of light to deviate from a light luminance level for each lighting region which light luminance level has been used to generate a conversion image signal. This generates an error in the luminance of the display image. Therefore, in the technique of Patent Literature 1, in order to compensate the error of the display image due to a deviation of the actual luminance of light from the light luminance level, a grayscale level of a final conversion image signal is generated by use of a correction look-up table in which correction table data corresponding to a combination of a light luminance level of a certain lighting region and a light luminance level of an adjacent lighting region is stored.
Citation List
Patent Literature 1
Japanese Patent Application Publication, Tokukai, No. 2002-99250 A (Publication Date: Apr. 5, 2002)
Non Patent Literature 1
Satoru KUBOTA and four others, “Television viewing conditions at home”, Journal of the Institute of Image Information and Television Engineers, Vol. 60, No. 4, pp. 597-603, 2006